Kay Phillips has been dreading this moment for a very long time.

The 59-year-old from Elon, North Carolina, has often wondered how much her commute cost her over the years. She decided to sit down and tabulate it once and for all for Reuters.

Specifically, the four years when Phillips was driving 2.5 hours each way to her job and back, every single workday. From little Granite Falls, up in the mountains of North Carolina's Caldwell County, to Chapel Hill for her job with the Adolescent Pregnancy Prevention Coalition of North Carolina.

The total tab, she figures: $43,000. And that is just in gasoline - not oil changes or repairs, not the value of her time.

"I always thought it would make me sick to find out," she says. "And it did."

And there's the rub. Even in less extreme circumstances, your commute is likely costing you much more than you realize - in driving-related expenses, in sheer number of hours on the road and in negative health outcomes.

In fact, 10.8 million Americans travel more than an hour each way to work. And 600,000 endure "megacommutes" of at least 90 minutes and 50 miles each way, according to the Census Bureau.

This was not what was supposed to happen. Indeed, in some utopian tech visions, it was expected that our commutes would eventually go away and we would all be working comfortably at home, tapping on our laptops and iPads while sipping chamomile tea.

"In terms of travel time, our national commute has been ridiculously stable," says Alan Pisarski, the Falls Church, Virginia-based author of the "Commuting in America," report series.

"In 2000, the average commute was 25.5 minutes. In 2011, it was 25.5 minutes. Literally, the variation was a tiny fraction of a single minute."

We often tend to dismiss commuting costs, as the necessary price of having a job. After all, especially in a difficult economic era, not everyone has the luxury of finding gainful employment within a short walk or bike ride from their home.

In fact the Gallup-Healthways Well-Being Index, which surveyed Americans about daily commutes and their effects, discovered a virtual horror show. They found the longer the commute, the higher the levels of one's obesity, cholesterol, pain, fatigue and anxiety.

What's more, the costs of commuting disproportionately hit those with modest incomes. For the working poor, commuting gobbles up roughly 6 percent of income - double the percentage of those bringing home higher salaries, says Robert Puentes, a senior fellow at the Metropolitan Policy Program for the Washington, D.C.-based Brookings Institution.

For the working poor who drive alone - instead of in carpools, for instance - that percentage rises to 8 percent to 9 percent of income.

"Those costs are so high, that it's actually changing the calculus of where people are willing to live," Puentes says.

BY THE MILE

Another useful way to calculate how much your commute is really costing you is by the mile.

Indeed, the personal-finance blogger Mr. Money Mustache - a 39-year-old Colorado resident named Pete who remains anonymous for his family's privacy, but who boasts over 4 million unique hits for his popular website - rails that when you crunch those numbers, you discover that a lengthy commute is "the biggest thing that is keeping most people poor."

"The IRS allows you to deduct your business driving at about 55 cents per mile, and this is based on a realistic addition of costs," he tells Reuters. "It is possible to beat the average by driving a smaller and more reliable car, but the cost is always much higher than just the price of gas.

"So if you have a 20-mile commute to work, multiply it out: 40 miles each workday times 50 cents a mile. And there are 2,500 of those workdays in every decade, so that 'not too bad' commute is burning at least $50,000 every ten years."

As for Kay Phillips, her commute was so spectacular that she actually got honored by auto-repair company Midas in its competition to find the American with the lengthiest trip to work. (She lost to the winner by only a little over 20 miles, one way.)

She has since moved and now enjoys a more modest daily commute of 35 miles each way - 40 minutes per trip tops, she says. But don't ask her how much all those prior commuting costs could have added up to for her retirement years.

After all, put $43,000 into an IRA or 401(k), compound it at even a modest rate of return, and you have a very nice nest egg indeed.

"Oh my goodness, don't go there," she says. "I don't even want to think about that."

(The writer is a Reuters contributor. The opinions expressed are his own.)